Characterization of a 2205 Duplex Steel Modified with Boron Obtained via Powder Metallurgy

Stainless steels are commonly used when a good balance between mechanical properties and corrosion resistance is required. Usually, to increase wear resistance, hard particles are added (carbides, borides, nitrides, and others) to the more ductile matrix (ferrite or austenite). The addition of boron to steels leads to the formation of primary and eutectic borides, which harden the material as solidified. Therefore, herein, the viability to prepare a modified 2205 duplex steel with 2.5 wt% of boron through powder metallurgy is investigated. The boron addition is performed in the atomization step. In addition, the effect of temperature in the sintering process is investigated, as well as the characterization of microstructure formation, phase transformations, and mechanical properties. The specimens are prepared from a prealloyed metal powder with three different granulometries: thick (250-500 & mu;m), medium (106-180 & mu;m), and thin powders (<45 & mu;m). Shaping is conducted by cold uniaxial compaction with sintering in a controlled Ar atmosphere. An optimal sintering temperature of 1200 & DEG;C is identified for all granulometries studied. However, the highest densification of >85% is observed with medium powder with an increase of nearly 40% in microhardness in comparison to the reference 2205 steel.